The pairing of same sex couples had previously been observed in more than 1,000 species including penguins, dolphins and primates.

However, in the latest study the authors claim the phenomenon is not only widespread but part of a necessary biological adaptation for the survival of the species.

They found that on the Hawaiian island of Oahu, almost a third of the Laysan albatross (large seabirds) population is raised by pairs of two females because of the shortage of males. Through these ‘lesbian’ unions, Laysan albatross are flourishing. Their existence had been dwindling before the adaptation was noticed.

Other species form same-sex bonds for other reasons, they found. Dolphins have been known engage in same-sex interactions to facilitate group bonding while male-male pairings in locusts killed off the weaker males.

A pair of “gay” penguins recently hatched an egg at a German zoo after being given the egg that had been rejected by its biological parents by keepers.

Writing in Trends in Ecology & Evolution, Dr. Nathan Bailey, an evolutionary biologist at California University, said previous studies have failed to consider the evolutionary consequences of homosexuality.

He said same homosexual behavior was often a product of natural selection to further the survival of the species.